Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/1a01ac108153b408eef4bf0f8d8a0f19.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563